High temperature bending creep behavior of a multi-cation doped α/β-SiAlON composite

SiAlON ceramics with high hardness and high toughness can be made through designing α/β-SiAlON composites. An important advantage of α-SiAlON phase is that the amount of intergranular phase is reduced by the transient liquid phase being absorbed into the matrix of α-SiAlON phase during sintering. But, the thermal stability of the α-SiAlON phase is an important concern for α/β-SiAlON composites especially at high temperatures. The use of different types of single or multiple cations during fabrication directly affects resultant microstructures and mechanical behavior of α/β-SiAlON composites. In this study, the creep behavior of a multi-cation (Y, Sm and Ca) doped α/β-SiAlON composite, in which aluminum-containing nitrogen melilite solid solution phase was designed as intergranular phase, was investigated by four-point bending creep tests under stresses from 50 to 150 MPa and at temperatures from 1300 °C to 1400 °C in air. The stress exponent was determined to be 1.6 ± 0.13 at 1400 °C and the creep activation energy was calculated to be 692 ± 37 kJ/mol⁻¹. Grain boundary sliding coupled with diffusion was identified as the rate-controlling creep mechanism for the α/β-SiAlON composite.     

Measurement invariance of the Gifted Rating Scales—School Form across five cultural groups.

This study examined measurement invariance of the Gifted Rating Scales—School Form (GRS–S) across the United States, Puerto Rico, China, South Korea, and Turkey, using multigroup confirmatory factor analysis. A total of 1,817 students were rated by 287 teachers using either translated versions of GRS–S or the original English GRS–S. Results indicate a similar factor structure for the GRS–S across the five locations; six factors with each of the 72 items equivalently loaded to the same latent variable across groups. The metric invariance test and the factor variance and covariance invariance tests reveal that the patterns of factor loadings and the factor variances and covariances are invariant across the five groups. Moreover, the scalar invariance test indicates that item means are equivalent across the groups. These results suggest that the GRS–S has intercultural utility and can be similarly interpreted. Implications and limitations of the present research for gifted identification are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tribological Behavior of TiAlN,AlTiN, and AlCrN Coatings at Boundary Lubricating Condition

In this study, ~?3.5 µm thick multilayer titanium alumina nitride (TiAlN), alumina titanium nitride (AlTiN), and alumina chromium nitride (AlCrN) coatings were deposited on the H13 steel surface by cathodic arc physical vapor deposition (CAPVD) method. The tribological performance of the coatings was evaluated by a tribometer at boundary lubrication condition. Then, coating surfaces were observed by optical microscope, optical profilometer, and atomic force microscope to evaluate the morphological changes, wear volumes, and tribofilm thickness. Also, scanning electron microscopy (energy dispersive X-ray) and X-ray photoelectron spectrometry analyses were applied to coating surfaces for the tribochemical evolution of the tribofilm. Results showed that AlCrN coating performed the best tribological behavior at boundary lubricated condition, when compared to TiAlN and AlTiN coatings and it can be used as a wear resistant cam tappet coating in internal combustion engines.     

Polyamide 6–Cellulose Composites: Effect of Cellulose Composition on Melt Rheology and Crystallization Behavior

Melt rheology and crystallization behavior of polyamide 6 (PA 6) and microcrystalline cellulose (MCC) composites were systematically studied in this research. The incorporation of MCC into the PA 6 matrix resulted in higher complex viscosities (|η*|), storage modulus (G′), and shear viscosities than those of neat PA 6, especially at low frequencies. The orientation of rigid molecular chains in the composites introduced by the addition of MCC induced a strong shear thinning behavior with an increase in MCC loading. The non‐isothermal crystallization kinetics of PA 6 and MCC composites were investigated by differential scanning calorimetry. The Avrami and Tobin model were applied to describe the process of non‐isothermal crystallization and to determine the crystallization parameters of the composites. Analysis of the crystallization kinetics indicated that the Avrami (n_a) and Tobin exponent (n_t) was altered by the MCC. It was also found that the Avrami and Tobin equations fit the empirical data well. POLYM. ENG. SCI., 54:739–746, 2014. © 2013 Society of Plastics Engineers     

Effect of various additives to marinating baths on some properties of cattle meat

Longissimus dorsi (LD) muscles obtained from young bull carcasses (Holstein Friesian) were marinated, using solutions containing 0.5% sodium tripolyphosphate (STP), 0.5% dicalciumhydrogen phosphate (CHP) and 0.5% citric acid (CA). All solutions, including a blank, contained 2% NaCl. Expressible moisture, cooking loss, marinade uptake, area gain (increase in slice size), colour coordinate values (L*, a*, b*), marinade and meat pH, and the textural properties of samples were evaluated. Marinating with STP and CHP solutions resulted lower cooking losses. Marinade uptake and area gain were lower for control steaks and steaks marinated with the CA solution. The highest lightness was found in steaks marinated with the CA solution. Steaks marinated with STP and CHP solutions were darker. The CA solution resulted in yellowness of steaks. All treatments significantly affected hardness, chewiness and resilience values of steaks. The lowest hardness value was found in steaks marinated with CA. STP and CHP treatments also improved tenderness.     

Deep-level Transient Spectroscopy of GaAs/AlGaAs Multi-Quantum Wells Grown on (100) and (311)B GaAs Substrates

Si-doped GaAs/AlGaAs multi-quantum wells structures grown by molecular beam epitaxy on (100) and (311)B GaAs substrates have been studied by using conventional deep-level transient spectroscopy (DLTS) and high-resolution Laplace DLTS techniques. One dominant electron-emitting level is observed in the quantum wells structure grown on (100) plane whose activation energy varies from 0.47 to 1.3 eV as junction electric field varies from zero field (edge of the depletion region) to 4.7 × 10⁶ V/m. Two defect states with activation energies of 0.24 and 0.80 eV are detected in the structures grown on (311)B plane. The E_c-0.24 eV trap shows that its capture cross-section is strongly temperature dependent, whilst the other two traps show no such dependence. The value of the capture barrier energy of the trap at E_c-0.24 eV is 0.39 eV.     

The integration of the corneal and limbal fibrils in the human eye

The precise orientation of the collagen fibrils in human cornea and sclera and the method by which these two areas fuse together at the limbus have never been determined, despite the importance of this information. From a consideration of the mechanics of the system, fibril orientation in the tissue has the potential to affect the curvature of the cornea so, by inference, refractive problems such as astigmatism involving an incorrect curvature of the cornea may be related to fibril orientation. The high intensity and small beam size of a synchrotron x-ray source has enabled us to study fibril orientation in post-mortem human cornea and sclera. Previously we have revealed two preferred directions of orientation in the cornea (Meek, K. M., T. Blamires, G. F. Elliot, T. Y. Gyi, and C. J. Nave. 1987. Curr. Eye Res. 6:841-846) and a circumcorneal annulus in the limbus (Newton, R. H., and K. M. Meek. 1998. Invest. Ophthalmol. & Visual Sci. 39: 1125-1134). Here we present the results of our investigation into the relationship between these two features. Our measurements indicate that the corneal fibrils oriented in the two preferred directions bend at the limbus to run circumferentially. On the basis of these results we propose a model as to how the human cornea and sclera fuse together.     

The appropriateness of use of percutaneous transluminal coronary angioplasty in New York State

Between 1974 and 1989 we prospectively observed 530 patients with brucellosis. The findings for 62 patients (42 males and 20 females; mean age, 34.7 years) with 63 episodes in which the sacroiliac joint was involved (the most frequent osteoarticular location [11.7%]) were analyzed. Ten of the older patients (mean age, 55.3 years) had concomitant spondylitis. Systemic symptoms were usually important, and characteristic pain and findings of sacroiliitis were observed in approximately 75% of cases. Blood cultures were positive for Brucella melitensis for 44 patients. The most frequent radiographic findings were blurring of articular margins (42 cases) and widening of the sacroiliac space (20 cases). No radiographic anomalies were detected in 13 cases. Results of 99mTc and gallium-67 bone scans were abnormal in approximately 90% of cases (abnormalities were often mild). Overall, clinical, radiographic, and isotopic bone scan findings were sensitive and useful, although they were occasionally minimal or difficult to evaluate, making diagnostic findings confusing or misleading. Brucellar sacroiliitis is a mild disease associated with a good outcome similar to that observed for patients with uncomplicated brucellosis.     

Fine needle aspiration cytology of papillary neoplasms

This article covers the fine needle aspiration biopsy cytomorphology of papillary carcinomas of different organs, differential diagnoses, and clinical correlation. Diagnostic problems and helpful cytologic features are emphasized. The purpose is to have a concise source of information that helps the pathologist to evaluate these neoplasms.     

Recurrent respiratory papillomatosis

Recurrent respiratory papillomatosis is a disease characterized by the growth of wart-like neoplasms anywhere along the aerodigestive tract. The etiologic agent is the human papillomavirus, of which 90 subtypes have been described. The age distribution of those affected appears to be a bimodal curve, with the first peak around 5 years of age and the second occurring in adults in the third decade of life. The mainstay of treatment is surgical resection to maintain an adequate airway; patients often require multiple surgeries. The epidemiology, pathogenesis, clinical features, and treatment options are discussed. Current evidence regarding prognosis and the multifactorial nature of pathogenesis are also reviewed.